Due to the enormous amounts of information that are transmitted or broadcast on today's telecommunication channels, most if not all such broadcast information is compressed due to the high level of information redundancy in video information. In this regard, there have been many different types and kinds of video information encoding schemes developed. Because of such diversity, the telecommunication industry in general has adopted standards that promote open and interoperable systems.
The most accepted standard proposed by the International Organization for Standardization (ISO) and the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) was promoted by the Moving Picture Expert Group (MPEG) and recently introduced as the 13818-2 specification for the coded representation of picture information. This standard which is known by those skilled in the art as MPEG2 compression of video information employs a variable bit rate method where the data rate is reduced for images with a low information content and increased for images with a higher information content.
While the syntax for coding video information into a single MPEG2 data stream is rigorously defined by the 13818-2 specification, the mechanisms for decoding such a MPEG2 data stream are not. Instead, the 13818-2 specification merely defines the results that must be achieved by such decoding.
The present invention describes a method for decoding two rows of encoded macroblocks concurrently, as opposed to the convention of decoding macroblock rows in raster order. Among other things, this new method enable the use of very small buffers for caching macroblock reference data.
Therefore, it would be highly desirable to have a new and improved method for caching encoded video information thus reducing memory bandwidth requirements while simultaneously enabling the decoding of the video information in a fast and efficient manner to produce the specific results required by the 13818-2 specification.